The House of Wisdom (7 page)

Catalonia enjoyed good trade relations with the Western Caliphate, based in the imperial city of Cordoba. Muslim traders were a common sight in Catalonian markets, and cultural trends, ideas, and inventions passed easily enough across this border between Muslim East and Christian West. The Arabs’ advanced science of the stars, the game of chess, the earliest representation of what came to be called Arabic numerals, and the Muslim astrolable—the most potent analog computer until the modern era—were all awaiting “discovery” in Catalonia.
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Here, all seven of the liberal arts were available for study.

At a time when even the richest monasteries of France, Germany, and England might own just a few dozen volumes of mostly outdated learning, the Catalonian monks, particularly those of Santa Maria de Ripoll, enjoyed access to relatively large collections that included Arabic texts and their translations. These hinted at the secrets of ancient learning, as well as more recent Arab science, philosophy, and medicine. Young Gerbert visited the Ripoll monastery and may have brought back knowledge of basic Arab technology, such as the workings of the water clock, to his native France. Nonetheless, even at Ripoll, the standard of learning was woefully weak. The earliest Latin treatises on the astrolabe and related technologies were peppered with errors and half-digested Arabic terminology; the West was unable to produce its own coherent astrolabe texts until the mid-twelfth century.
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Gerbert returned home from Catalonia to take up a series of teaching posts. He immediately championed the very quadrivium—music, arithmetic, geometry, and astronomy—that he had been unable to pursue as a young monk in France. During his stay in Spain, he had acquired the translation of an Arabic book on the stars from the archdeacon of Barcelona and a separate work on mathematics and astronomy. Gerbert taught his students arithmetic by means of an unusual abacus consisting of individually numbered counters, one to nine; the concept of zero remained elusive. Soon, similar Latin abacus systems with the Hindu-Arabic characters—the figures we use today—in place of the prevailing Roman numerals, using crude transliterations from the original Arabic names for each figure, began to take root. The names for the figures were likely borrowed from the informal Arab practice of calculating on a dust board, a form of erasable easel. It would take another 150 years for proper Arabic numerals and the positional system of ones, tens, hundreds, and so on—fundamentally the same system we use today—to become the accepted means of calculation.
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Gerbert and his followers were fascinated by the course of the stars and the planets, and they insisted on the value of firsthand observation of the heavens—work that at the very least prepared the way for the coming of Arab astronomy. In a letter from the French city of Rheims to a fellow cleric around 978, Gerbert makes clear that he has broken free from the flat-earth teachings of Isidore of Seville. “In reply to your query about the sphere for demonstrating the celestial circles and constellations, my brother, it is made completely round, divided equally through the middle by the circumference, which has been divided into sixty parts.”
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Medieval commentators hold that Gerbert was the first to introduce the West to the astrolabe as a way to address the troubling problems of monastic prayer time and the ecclesiastical calendar. This portable instrument could also measure the height of a tower or the depth of a well, determine geographic latitude, mark the direction of true north, and work out the position of the sun and the major stars. The origins of the device itself are obscure, but the design and theoretical approach were almost certainly Greek. Greek mathematicians and astronomers in Alexandria, Egypt, wrote numerous treatises on the basics of the astrolabe. A text by Ptolemy, now lost, detailed the underlying mathematical principles, also vital to mapmaking, but the more advanced planispheric astrolabe used by the Arabs was unknown in his day. Arab tradition, nonetheless, credits the great astronomer with the accidental invention of this powerful tool. Ibn Khallikan, writing in the thirteenth century, recounts one version: Ptolemy was out riding one day, a celestial globe in his hand; he dropped it, and his horse crushed it flat with his hooves, creating the planispheric astrolabe.
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Refined by the Arabs from these early Greek designs, the astrolabe was a virtual bronze book of the stars that projected the spherical universe onto a two-dimensional face. A treatise on the astrolabe, commonly ascribed to Gerbert or a member of his immediate circle, calls the device a great gift from God but also appears to warn against any broader usage: “[The astrolabe can be used] to find the true time of day, whether in summer or wintertime, with no ambiguous uncertainty in the reckoning. Yet this seems most suitable for celebrating the daily office of prayer and to be excessive knowledge for general use. How pleasing and seemly the whole proceeds, when with the greatest reverence at the proper hour under the rule of a just judge, who will not wish the slightest shadow of error, they harmoniously complete the service of the Lord.”
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The astrolabe itself was beautiful to behold—elegant in form and powerful in function. The typical device was about the size of a salad plate, fashioned in polished, decorative bronze. Degrees of latitude, or perhaps the hours of the day, were commonly inscribed along the outer edge. A disk, painstakingly calibrated for the user’s geographic location, sat atop the face of the astrolabe, with a rotating skeinlike cutout displaying the principal stars and the sun’s annual path affixed to that and held in place with a wedge-shaped pin known as the horse. A pivoting pointer—the alidade, from the Arabic
al-idada
—was mounted on the back to take readings while the astrolabe was held aloft, suspended at arm’s length, by a ring at the top. In the daytime, the rays of the sun were lined up with two pinholes or notches in the alidade; at night, the user followed the same procedure but took aim at a known star. The position of the alidade against the astrolabe’s scaled markings could then yield a wealth of corresponding celestial information. The perfection of the astrolabe reflected the genius of Arab science: it drew on classical sources but then went well beyond them to refine the device and to address the burning questions of the day in such fields as timekeeping, astronomy, astrology, and cartography.

As the early Latin scholars immediately recognized, however, descriptions of the workings and utility of the astrolabe cannot do it justice. In one of the earliest Latin references to the device, Radolphus, a teaching master at Liege, invites a colleague from Cologne to come and handle the astrolabe for himself, rather than rely on any written account or sketch that he might provide. “Otherwise, only to see the astrolabe will be of no more help than drawings for the … blind, or poultices for the gout-ridden,” Radolphus informs his learned friend in a letter.
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Word of the astrolabe and its Arab provenance began to spread slowly throughout the West. Fulbert, a student of Gerbert and later the bishop of Chartres and the founder of its influential cathedral school, composed a short verse to help his pupils recall the Arabic names of eight of the most important stars in the constellations of the Western zodiac. The result is the earliest known use of Arabic words in a Latin text: “Aldeberan stands out in Taurus, Menke and Rigel in Gemini, and Frons and bright Cabalazet in Leo. Scorpio, you have Galbalgrab; and you Capricorn, Deneb. You, Batanalhaut [literally,
batan al~hut
, fish’s gut], are alone enough for Pisces.”
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These same “stars of the hours” appear in one of the earliest European works on the astrolabe, dating from around 1000. Fulbert also prepared a glossary of Arabic and Latin names for parts of the astrolabe, opening the door to what would soon become a flood of Arabic terminology, concepts, and ideas in Western arts and sciences.
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Today, our constellations and planets bear Latin names, but those of many of the major stars are Arabic in origin.

Gerbert’s influence was particularly strong in Lotharingia, and he kept up a lively correspondence with a number of scholars in the region about the latest mathematical trends and ideas he had picked up in Spain. Loose ties between the local monasteries and those still active in Muslim Spain had already established pathways for the occasional exchange of ideas, and Germany and the Western Caliphate enjoyed periodic contact. A delegation sent to Cordoba in 954, headed by a well-traveled Lotharingian scholar, John of Gorze, is thought to have returned after a three-year stay with original manuscripts and a few early translations of Arabic manuscripts. The Spanish caliph Abd al-Rahman responded by dispatching a Mozarab, or Arabized Christian, as his representative to the Saxon court. From the schools and monasteries of Lotharingia, Arabic learning began to spread gradually into Germany, France, and England.
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Not everyone was so captivated by the arrival of these new ideas, with their seemingly magical powers and their suspicious association with the infidel Arabs. In a society where literacy and general education were rare, this same suspicion was easily directed at any type of nonreligious book learning. This trend would only be aggravated by the coming intellectual invasion from the Muslim world, with its foreign terms, mysterious symbols, and unimaginable innovations. Allegations of black magic were hurled at a number of the early Christian scholars who sought out Arabic learning, a phenomenon that would later see the deadly charge of heresy leveled against those who challenged church teachings in philosophy and the natural sciences.

William of Malmesbury, a monastic librarian and historian who died 140 years after Gerbert d’Aurillac, acknowledged the late pope’s undoubted technical skills but nonetheless remained wary of his time in Spain: “There he learned what the singing and flight of birds portended, there he acquired the art of calling up spirits from hell.”
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William also dismissed Gerbert’s mathematical ideas as “dangerous Saracen magic” and claimed that his election as pontiff, on the cusp of the millennium in 999, was due to a pact with the Devil. Another cleric noted sourly that, like Gerbert before him, the learned bishop of Hereford, Robert, had also wasted his time with such matters:
“Mathesis
[astrology] did not prolong his life, nor did the abacus which numbers years in a different way.”
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A thirteenth-century tradition calls Gerbert “the best necromancer in France, whom the demons of the air readily obeyed in all that he required of them by day and night, because of the great sacrifices he offered them.” These same demons, it was said, taught him to use the wondrous astrolabe in exchange for his soul.
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In Gerbert’s day, these fears of Arab science had not yet crystallized into active clerical opposition, and they certainly did nothing to derail his brilliant career. After an appointment as personal tutor to the son of Otto, the Holy Roman emperor, he traveled to Rheims, where he taught logic and philosophy and later became the head of the cathedral school. Students from far-off corners of Europe flocked to his lectures. Yet just four years before his elevation to the papacy, Gerbert still evoked bitter opposition in some quarters for his worldly and unorthodox outlook. Philosophy, even what little was known of the classics, was still suspect. “The vicars of Peter and their disciples will not have for their teacher a Plato, a Virgil, or any other of that vile herd of philosophers,” the papal legate protested to no avail.
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The Arab-based learning of Gerbert faced more than just the doubts of the clergy and the fears of the superstitious masses. It was also precariously prone to error, misunderstanding, and at times some comic confusion. Gerbert and his students may have represented the brightest lights of their generation, but they were wholly unable to absorb or even comprehend the full reach of Arabic science, with its profound grounding in Aristotelian metaphysics and Greek, Persian, and Hindu learning in general. The most basic concepts of geometry posed a problem. Two of Gerbert’s leading pupils exchanged earnest letters around 1025 in an unsuccessful effort to discern just what the classical geometers might have meant by the interior angle of a triangle, a mystery they never resolved. Nor were they able to work out any geometric theorems. One reports his excitement at having acquired an astrolabe of his own. Stumped by such an elementary matter as the interior angle, they would have been completely unable to comprehend the geometric theory that lies behind the device.
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For this first generation touched ever so slightly by Arab learning, new devices like the astrolabe and the abacus, and new concepts like the Hindu-Arabic numeral system, remained just that—devices to be exploited rather than fully understood. These pioneers were far more concerned with practical use than with theoretical knowledge, more invested in the how than in the why. There was so far no serious attempt to master the underlying Arab knowledge of the heavens, developed over hundreds of years and captured so brilliantly in the polished face of the bronze astrolabe. Nor was there any real appreciation of the broader implications—for the church, for society, or for mankind in general—of this new learning from the East. They were content simply to try to determine the prayer times and make other basic measurements, much as the user of a modern pocket calculator or personal computer may produce accurate results without any real understanding of mathematics.

With much of Bath in ashes after the failed uprising against him, the victorious William the Red turned to Bishop John de Villula in 1088 to restore order and to reconstruct the town’s famous monastery. Eager to secure the loyalties of so able a retainer, the new monarch sold the city to John for five hundred pounds of silver and allowed him to move his see from the unfortified town of Wells to the relative safety of Bath and its surviving stone walls. John’s interest in Bath, however, extended well beyond simple political or military considerations. The town was closer to Worcester and the monasteries of the Severn basin, emerging centers of English learning that John found highly inviting.
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